<!DOCTYPE html>
<html lang="zh_CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #id1{
            /* 内容区 */
            width: 300px;
            height: 300px;
            /* 边框 */
            border-width: 10px;
            border-color: blue;
            border-style: solid;
        }
    </style>
</head>
<body>
    <!-- 盒子包括：内容，内间距，边框，外间距 -->
    <DIV id="id1">hahah</DIV>
</body>
</html>